1. Field of the Invention
This invention relates to the structure of a welding torch weaving device, and more particularly to machine geometry capable of adjusting a two-dimensional weaving pattern with ease and flexibility.
2. Description of the Prior Art
With the development of semi or completely automatic welding techniques, a variety of devices have been utilized to weave welding torches in CO.sub.2, MIG and non-gas welding processes. There have been generally two types of weaving techniques: (1) varying only the weaving amplitude with the weaving pattern unchanged (one-dimensional weaving) and (2) varying the weaving pattern per se according to variations in groove shape, etc. (two-dimensional weaving).
In the former case, patterns are linear and circular and an example of the machine geometry is depicted in FIG. 1. A weaving device 1 includes a cam 3 attached to an output shaft of a motor 2 mounted on a frame 5 and a rotary plate 4 supported slidably on a support board 7 rotatable on part of the frame 5. A welding torch 8 is lodged on the point of the rotary plate 4 having the opposite end thereof in which an elongated slot 4' is formed to receive the cam 3 therein. A roller 6' is disposed on a rear end of the rotary plate 4 and held in an elongated slot 6 in a wall 5' integral with the frame 5. If the motor 2 is energized, the rotary plate 4 starts rotating about the support board 7 to weave the torch 8. This behavior of the torch is one dimensional and the weaving pattern is not variable per se although the amplitude and speed are easily changeable.
In order to increase the welding amount per bath or to avoid poor fusion welding imperfections, such as inclusion of slag, weaving has been extensively studied and investigated. Some welding machines have been accompanied by two dimensional weaving devices.
Various two dimensional patterns are illustrated in FIG. 2 and are fully available for vertical butt welding, fillet welding, etc. The prior art weaving device developing such a two dimensional pattern generally combines two rotating movements through the use of gears and cams whether it includes a combination of multiple drive sources or a common drive source. The former uses individual motors for X axis and Y axis movements to describe in combination patterns such as a triangle and a trapezoid. The latter is disclosed in Japanese patent publications No. 51/12457 and No. 51/20345, for instance, wherein a single motor drives two gears for two different vibrations to describe two dimensional patterns. Those prior art weaving devices are thus complicated in structure and large in dimension and often suffer from low reliability. They are useful within only a limited range of applications such as special purpose automatic welding machines for a particular welded joint.
With the recent development of automatic welding machines compatible with various welding devices and various welding positions, it is most desirable that the weaving device have a higher welding efficiency, higher reliability, a simplicity of structure, a smaller size and be easy to handle through the use of a control circuit. The present inventors have earlier developed a small sized and effective weaving mechanism which easily weaves a torch in a two dimensional manner. Further investigation has been conducted to seek a weaving device having excellent wear resistance and stable operation for prolonged use.
As a consequence of this investigation, the Applicants succeeded in enhancing wear resistance through a combination of links while basically retaining the concept of the earlier weaving device.